Fig. 1. Temperature control system block diagram of butterfly semiconductor laser

Fig. 2. Schematic of TEC drive circuit

Fig. 3. Working principle of TEC

Fig. 4. PSO algorithm flow chart

Fig. 5. Simulation model of temperature control system

Fig. 6. Traditional PID optimization curve

Fig. 7. PSO optimization curve

Fig. 8. Improved PSO optimization curve

Fig. 9. Simulation waveform of temperature control system model

Fig. 10. PID parameter optimization curve

Fig. 11. Photo of butterfly semiconductor laser driver circuit

Fig. 12. Traditional PID temperature stability curve

Fig. 13. PSO temperature stability curve

Fig. 14. Improved PSO temperature stability curve